Overhead ceiling fans have been used for many years in to help move air in rooms. Traditional blades have usually centered around flat planar rectangular type shapes. See U.S. Pat. No. Des.355,027 to Young and U.S. Pat. No. Des.382,636 to Yang. Although both Young and Yang and 1995 and 1997 patents, respectively, both patents use technology similar to that from the turn of the century namely, flat planar type blades. None of these patents nor any ceiling fan technology known to the inventor, has optimized the ceiling fan blade shapes for optimum aerodynamic airflow. Furthermore, other known problems exist with the traditional flat planar rectangular ceiling fan blades. Traditional blades can be noisy at high speeds. These traditional blades have also been prone to vibration and wobbling during use.
Aircraft, boat and automobile engine propeller type blades have been altered over time to other shapes besides planar rectangles. See for example U.S. Pat. No. 4,411,598 to Okada; U.S. Pat. No. 4,730,985 to Rothman et al.; U.S. Pat. No. 4,794,633 to Hickey; U.S. Pat. No. 5,114,313 to Vorus; and U.S. Pat. No. 5,253,979 to Fradenburgh et al. However, all of these patents are used for high speed water and air craft and automobile engine applications where the propellers are run at high revolutions per minutes(r.p.m.) generally in excess of 500 r.p.m. None of these air craft and boat propellers are designed for optimum airflow at low speeds approximately 50 to approximately 200 r.p.m., which is the approximate r.p.m. used in overhead ceiling fans.
Some alternative shapes have been proposed for ceiling fan blades. See U.S. Pat. No. 4,892,460 to Volk. However, the Volk patent while claiming to be "aerodynamically designed" requires a curved piece to be attached by a groove to the side conventional planar rectangle blade. Using two pieces for each blade adds extreme costs in both the manufacturing and assembly of ceiling fan itself. Furthermore, the grooved connection point in the Volk devices would appear to be susceptible to separating and causing a hazard to anyone or any property beneath the ceiling fan itself. Such an added device also has necessarily less than optimal aerodynamic properties.
Thus, the need exists for solutions to the above problems in the prior art.